Abstract：The distribution of Al atoms in the framework of FAU-typed zeolite and its impact on Brønsted acid strength were investigated by the combination of quantum mechanics and molecular mechanics (QM/MM). The corresponding Al/Si substitution energy and deprotonation energy of different Al number zeolite cluster were calculated. Results show that Al atoms are uniformly distributed if the number of Al atom in sodalitecage is less than 6. When the number of Al atom is greater than 7, the additional Al atoms are in a random location, causing the decreasing of zeolite skeleton structure stability. Al atoms preferentially distribute in the six-member ring of supercage unit, and then alternately locate in the four-member ring. Brønsted acid strength is nonlinear decreasing along with the rising of the number of Al atom in sodalitecage. Electron inducement by Next-nearest-neighbor （NNN） Al atom is stronger than that of Next-next-nearest-neighbor （NNNN） Al atom, which polarizes the protons attributing to Brønsted acid sites. The amplitude of variation of acid strength becomes even larger along with the increases of the number of NNN-Al atoms.
